"The high churn and low bandwidth characteristics of peer-to-peer
(P2P) backup systems make recovery a time consuming activity that
increases
system's outage. This is especially disturbing from the user
perspective, because
during outage the user is prevented from carrying out useful work.
Nevertheless,
at any given time, a user typically requires only a small fraction of
her data to
continue working. If the backup system is able to quickly recover such
files, then
the system's outage can be greatly reduced, even if a large portion of
the data
lost is still being recovered. In this paper, we evaluate the use of a
file system
working set model to support efficient recovery of a P2P backup system.
By exploiting
a simple LRU-like working set model, we have designed a recovery
mechanism
that substantially reduces outage and allows the user to return faster
to
work. The simulations we have performed show that even this simple model
is
able to reduce the outage by as much as 80%, when compared to the
state-ofpractice
in P2P backup recovery."